Calluses are areas of thickened skin that may occur on the hands or feet and can be caused by persistent rubbing or uneven pressure, for example from ill-fitting shoes. They have a tendency to form over bony prominences and with regards the feet, they are most commonly found at the heel, the ball of the foot and the sides of the toes. On the hand they typically form on the underside of the fingers or on the palm. Calluses are often unsightly, and the thicker they are the more yellow they can look. With time, particularly thick calluses can become cracked and painful.
There are a number of known methods for reducing or removing calluses, generally based upon rubbing, scraping or cutting the hardened skin away. In many cases this may include a first step of softening the skin by soaking the feet or hands in water or by applying some form of softening lotion to the hard skin. The hard skin can be reduced or removed using a device with an abrasive surface, such as a pumice stone, emery board or a device with carborundum paper attached to it. These devices can be manual or electrically operated and in the latter case, an abrasive head can be vibrated and rotated over the hard skin. Examples of such devices are described in WO03/022175.
The known abrasive devices have a number of drawbacks. In many cases they are unable to conform to the curvature of the parts of the hands or feet where calluses usually occur. In addition, abrasive surfaces tend to wear out with time and they can be difficult to clean, potentially leading to hygiene issues.
The majority of the prior art devices which remove skin with a cutting action incorporate one or more flat metal blades, such as a razor blade or the like. U.S. 2005/0061343 discloses an example of such a cutting device in which a cutting blade is mounted in a head piece attached to a handle in order to be placed in contact with the skin and pulled across the callus for removing a thin layer of skin, the process being repeated as required. Such devices which shave off layers of skin are difficult for untrained people to use safely and often do not discriminate well between callused and healthy skin, so that they can present a significant risk of injury, e.g. due to cutting as a result of the blade being positioned incorrectly or being manipulated so that too much skin is removed.
Some known cutting devices are equipped with one or more curved blades instead of flat blades, the idea being that curved blades will conform more closely to the shaped surface of the foot or hand. An example of such device is described in U.S. 2007/0244491. There are also known callus removers with blades in the form of rasp foils which have a resemblance to cheese graters. These devices are subject to the same drawbacks as outlined above for devices with flat blades.
Another approach to a callus-cutting device is described in U.S. 2007/0240730 and consists of a single stainless steel tube, one end of which is sharpened at its inner edge to provide a circular cutting edge. This callus remover is used by holding the tube perpendicular to the skin and moving the cutting edge back and forth with a reciprocating action for scraping off hard skin. The device is small and difficult to handle. Also, although the scraping effect is optimum when the tube is held perpendicular to the skin, users tend to hold it at an angle, which can make it ineffective or lead to excessive cutting depth.
In U.S. 2008/0230081 there is described a device for removing hard layers of skin, having a body in the form of a disc with several concentric blade edges integrally formed on one side. One embodiment includes a number of such discs disposed in a rectangular array on one side of a planar member having a handle attached at one end, this device being made by injection moulding. The effectiveness of the individual blade edges is impaired due to the proximity and large number of blade edge portions that are configured to contact the skin at the same time.